Various proposals have been made for apparatus for use in unloading grain from a grain bin. These include various bin sweeps, which are devices for drawing grain across the bin floor to the inlet of a main unloading auger. Problems with the known devices include the length of the sweep, which must be short enough to fit into any bin to be swept but long enough to provide an efficient sweeping of all parts of the largest bin to be unloaded and manipulation of the sweep to cover the entire bin floor.
Bin sweeps which are attached at the lower end which is the feed end of a main auger are well known and arranged to be coupled to the lower end of the main auger to be driven by that lower end and include a helical flight to sweep the material from the bin toward the lower end for transportation along the main auger. An example of this device is shown in U.S. Pat. No. 2,640,577 (Roscoe). These devices have many disadvantages in that they do not fully sweep the floor area of the bin leaving the user to carry out much shoveling. In particular the sweep cannot rotate fully around the lower end of the auger and is limited to a certain arc within the bin. In addition the sweep is of a fixed length so that it cannot accomodate different sizes of bins.
Another example of a device of this type is shown in U.S. Pat. No. 2,763,362 (Greaves) which shows a sweep of this general type which is coupled together in three lengths to attempt to increase the amount of area which can be swept but again there are many problems. A further older device is shown in U.S. Pat. No. 2,393,572 (Soma) which provides again a sweep of limited action but in this case the material is discharged through an air duct out of the bin. The sweep itself however retains the difficulty of covering the full area of the bin.
A more recent device is shown in U.S. Pat. No. 4,669,941 (West) which shows a device which can pivot around a fixed point within a bin but again the sweeping arc of the device is limited and the device is necessarily fixed within a particular bin and cannot be used with more than one bin.
A yet further device is shown in the more recent U.S. Pat. No. 4,824,312 (Schiltz) which discloses a fixed duct mounted within the bin which extends from one wall to a central position at which there is a vertical auger section. At the bottom end of the vertical auger section is coupled a sweep auger which can rotate 360.degree. around the bin floor. The sweep auger can be decoupled and removed but the remainder of the equipment remains coupled within the bin.
This device therefore has a number of disadvantages. Firstly the main part of the device remains fixed within a bin and therefore each bin requires a separate piece of equipment at accumulatively high cost. Secondly the device is associated with a particular diameter of bin and cannot be used with other types of bins. Thirdly the coupling between the auger section which extends outwardly of the wall of the bin, the vertical section and the sweep section is obtained by gear boxes located inside the auger tubes which thus seriously restrict the amount of flow which is obtained and thus significantly increases the amount of time necessary for cleanout of the bin. Furthermore the sweep auger section has a shroud around a rear part of the auger section to assist in transportation of the material but otherwise is uncovered and is driven by a large wheel at the outside end. This drive system will cause the auger once freed from the material to move rapidly around the floor of the bin which can be very dangerous to any user within the bin. Furthermore the exposure of the flight is again very dangerous in that the rapidly moving sweep can seriously damage the legs of the user if caught unawares within the bin.
Flexible couplings provided in an auger system are known for example in U.S. Pat. No. 3,092,241 (Dubie), 3,709,357 (Brown) and 3,727,746 (Slusher). The first of these patents provides a flexible sleeve formed in a plurality of movable sections together with a flexible core within the sleeve which carries a plurality of separate collars. However this provides a construction which has a very gradual radius of curvature so that the material must be lifted to a relatively high level by the inefficient auger system at the curved section thus significantly reducing the speed of transport of the material. In addition the design shown is totally unsuitable for use as a device for removing material from a bin. The further two patents of Brown and Slusher simply disclose flexible auger flights which curve around a required corner but which are unsuitable for use with particular material.
Auger systems which can be expanded or contracted in length are also known from U.S. Pat. Nos. 4,356,910 (Togstad), 2,845,167 (Hieken), and 3,605,995 (Maack). In each of these cases an auger system includes a telescopic sleeve and an auger flight formed from two portions one of which can be screwed relative to the other to increase and decrease the amount of overlap between the two flight sections. In Heiken the movement is obtained by rotating an inner drive element carrying one flight portion relative to an outer drive element to thus provide the screw action following which the inner and outer drive elements are coupled by a transverse pin holding the auger at the required length. In Maack, the length of the device is controlled by fixing the length of the outer sleeves. In Toggstad the total length of the auger is controlled by either a cylinder system which moves the telescopic tube in and out or as shown in the drawings by a threaded rod which locks the outer end of the sleeve relative to the outer end of the first flight section. These devices are therefore difficult to adjust and accordingly are unsuitable for use where rapid adjustment is required for example in a bin sweep.
The present invention addresses these and other problems with known bin sweeps and sweep auger combinations.